This application claims priority to German Application No. 10025586.8 filed May 24, 2000.
The invention relates to a drive train for a motor vehicle, and in particular, to a drive train for a motor vehicle with which the wheel torque is constant and notches in the torque are avoided.
In automatic transmissions, it is preferable to carry out gear shift operations as quickly and comfortably as possible. In this respect, the acceleration values, the wheel torque values on which the latter are based and the xe2x80x9cjerkxe2x80x9d or jerking of the drive train (which is derived therefrom) are decisive for the driver""s perception.
In a conventional automatic transmission, constant comfortable gear shift operations are achieved, inter alia, by reducing the engine torque during the gear shift operation with an xe2x80x9cengine interventionxe2x80x9d by adjusting the ignition angle in a way which is adapted to the load (German periodical ATZ 93 (1991) Issue 9, pages 504-519). Details on a signal which can trigger the engine intervention are not given in the periodical, neither are measures for increasing comfort when performing gear shift operations by making the wheel torque constant.
A typical starter system for an internal combustion engine contains an electric machine whose rotor is connected fixed in terms of rotation, either directly or via a speed transforming transmission, to the crankshaft of the internal combustion engine in order to accelerate the internal combustion engine at least to a starting engine speed which is necessary for starting up (DE 198 17 497 A1).
The subject matter of application (DE 199 06 871 A1) describes a method for actuating an engine in a drive system which contains an automated transmission and an automated clutch, which optionally couples the engine to the transmission in order to transmit torque. If a gear shift operation is to take place, a prediction profile for an operating variable which characterizes the operating state of the engine is predefined for a time period of the gear shift operation. The engine is controlled in accordance with the predefined prediction profile in such a way that the deviation between the operating variable and the prediction profile is minimized.
In one embodiment of the invention, there is a drive train for a motor vehicle. The drive train includes, for example, an engine which is controlled by an engine controller, a transmission which is controlled by a transmission controller, and a data link between the engine controller and the transmission controller. The signals are exchanged during a gear shift operation of the transmission, sensor signals being transferred from the engine controller to the transmission controller and an intervention signal being transferred from the transmission controller to the engine controller, by means of which intervention signal the engine is controlled by the engine controller during the driving mode of the motor vehicle, the intervention signal has a plurality of values by which the engine torque is reduced with the engine controller during the gear shift operations of the transmission, the engine speed is adjusted to a predefined value, the engine torque is switched over to a new setpoint value and a jerk control is carried out by adjusting the engine speed.
In one aspect of the invention, the intervention signal has an initial value in which a normal driving mode applies without a gear shift operation, a first value in which a torque control is carried out, a second value in which a slow engine speed adjustment is carried out, a third value in which a torque control is carried out and a fourth value in which a rapid engine speed adjustment is carried out with the drive train closed.
In another aspect of the invention, a mixed engine torque and engine speed control is brought about by the second value of the intervention signal.
In yet another aspect of the invention, a torque adjustment is carried out by the first and third values of the intervention signal.
In still another aspect of the invention, the intervention signal has an initial value in which normal driving mode applies without a gear shift operation, a fifth value in which shift up operation is carried out, a sixth value in which the motor vehicle is accelerated, and a seventh value in which a shift down operation is carried out.
In one aspect of the invention, a combined engine torque and engine speed control is carried out at the fifth value of the intervention signal.
In another aspect of the invention, the engine speed is accelerated at the sixth value of the intervention signal.
In yet another aspect of the invention, an engine speed adjustment is carried out at the seventh value of the intervention signal.
In still another aspect of the invention, the drive train includes an engine which is embodied as a crankshaft starter generator.
In still another aspect of the invention, a rapid engine speed adjustment is performed to a predefined absolute value using the crankshaft starter generator.